package envoy.event;

import static envoy.event.ElementOperation.*;

import envoy.data.*;

/**
 * This event is used to communicate changes in the group size between client and server.
 * <p>
 * Possible actions are adding or removing certain {@link User}s to or from a certain {@link Group}.
 *
 * @author Leon Hofmeister
 * @since Envoy Common v0.1-beta
 */
public final class GroupResize extends Event<User> {

	private final long				groupID;
	private final ElementOperation	operation;

	private static final long serialVersionUID = 0L;

	/**
	 * Initializes a {@link GroupResize} through a Contact where the name has already been set.
	 *
	 * @param user      the {@link User} who wants to join or leave a group
	 * @param group     the {@link Group} he wants to join or leave
	 * @param operation describes what to do with the given user:<br>
	 *                  add him to this group or remove him from it
	 * @since Envoy Common v0.2-alpha
	 */
	public GroupResize(User user, Group group, ElementOperation operation) {
		super(user);
		this.operation = operation;
		final var contained = group.getContacts().contains(user);
		if (contained && operation.equals(ADD))
			throw new IllegalArgumentException(String.format("Cannot add %s to %s!", user, group));
		else if (operation.equals(REMOVE) && !contained)
			throw new IllegalArgumentException(
				String.format("Cannot remove %s from %s!", user, group));
		groupID = group.getID();
	}

	/**
	 * @return the ID of the {@link Contact} this event is related to
	 * @since Envoy Common v0.2-alpha
	 */
	public long getGroupID() { return groupID; }

	/**
	 * @return the operationType
	 * @since Envoy Common v0.1-beta
	 */
	public ElementOperation getOperation() { return operation; }

	/**
	 * Applies the operation to a group.
	 *
	 * @param group the group to resize
	 * @since Envoy Common v0.2-beta
	 */
	public void apply(Group group) {
		switch (operation) {
			case ADD:
				group.getContacts().add(value);
				break;
			case REMOVE:
				group.getContacts().remove(value);
				break;
		}
	}

	@Override
	public String toString() {
		return String.format("GroupResize[user=%s,groupid=%d,operation=%s]", get(), groupID,
			operation);
	}
}